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Open AccessJournal ArticleDOI

Type Ia supernova discoveries at z > 1 from the Hubble Space Telescope: Evidence for past deceleration and constraints on dark energy evolution

TLDR
For a flat universe with a cosmological constant, the transition between the two epochs is constrained to be at z = 0.46 ± 0.13 as mentioned in this paper, and w = -1.02 ± (and w < -0.76 at the 95% confidence level) for an assumed static equation of state of dark energy.
Abstract
We have discovered 16 Type Ia supernovae (SNe Ia) with the Hubble Space Telescope (HST) and have used them to provide the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration. These objects, discovered during the course of the GOODS ACS Treasury program, include 6 of the 7 highest redshift SNe Ia known, all at z > 1.25, and populate the Hubble diagram in unexplored territory. The luminosity distances to these objects and to 170 previously reported SNe Ia have been determined using empirical relations between light-curve shape and luminosity. A purely kinematic interpretation of the SN Ia sample provides evidence at the greater than 99% confidence level for a transition from deceleration to acceleration or, similarly, strong evidence for a cosmic jerk. Using a simple model of the expansion history, the transition between the two epochs is constrained to be at z = 0.46 ± 0.13. The data are consistent with the cosmic concordance model of ΩM ≈ 0.3, ΩΛ ≈ 0.7 (χ = 1.06) and are inconsistent with a simple model of evolution or dust as an alternative to dark energy. For a flat universe with a cosmological constant, we measure ΩM = 0.29 ± (equivalently, ΩΛ = 0.71). When combined with external flat-universe constraints, including the cosmic microwave background and large-scale structure, we find w = -1.02 ± (and w < -0.76 at the 95% confidence level) for an assumed static equation of state of dark energy, P = wρc2. Joint constraints on both the recent equation of state of dark energy, w0, and its time evolution, dw/dz, are a factor of ~8 more precise than the first estimates and twice as precise as those without the SNe Ia discovered with HST. Our constraints are consistent with the static nature of and value of w expected for a cosmological constant (i.e., w0 = -1.0, dw/dz = 0) and are inconsistent with very rapid evolution of dark energy. We address consequences of evolving dark energy for the fate of the universe.

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Cosmological parameters from supernova observations: A critical comparison of three data sets

TL;DR: In this paper, Padmanabhan and Choudhury extended their previous analysis of cosmological supernova type Ia data to include three recent compilation of data sets.
Journal ArticleDOI

Interacting holographic generalized Chaplygin gas model

TL;DR: In this paper, a correspondence between the holographic dark energy density and interacting generalized Chaplygin gas energy density in FRW universe is considered. And the potential of the scalar field is reconstructed to describe the generalized Chapleygin cosmology.
Journal ArticleDOI

Holographic dark energy models: a comparison from the latest observational data

TL;DR: In this article, the authors performed the best-fit analysis on three holographic dark energy (HDE) models, namely, the original holographic HDE model, the agegraphic RDE model and the holographic Ricci dark energy model.
Journal ArticleDOI

Dynamical vacuum energy, holographic quintom, and the reconstruction of scalar-field dark energy

TL;DR: In this article, a scalar-field model is used to simulate the evolving behavior of the dynamical vacuum energy and reconstructing this scalar field model according to the fits of the observational dataset.
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Matter instability in modified gravity

TL;DR: In this paper, the Dolgov-Kawasaki instability in the matter sector of the modified gravity scenario incorporating a $f(R) correction to Einstein gravity is studied in general.
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Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds

TL;DR: In this article, a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed, is presented.
Journal ArticleDOI

Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds

TL;DR: In this paper, the authors presented a reprocessed composite of the COBE/DIRBE and IRAS/ISSA maps, with the zodiacal foreground and confirmed point sources removed.
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